Tool, cutter and button disk

ABSTRACT

A tool for mining rock by means of undercutting includes an attachment part which defines a center longitudinal axis, and a holder mounted to the attachment part by bearings for rotation relative thereto about the axis. An outer surface of the holder includes a circumferentially extending first groove. A button disk is mounted on the cutter and includes an inner surface having a circumferentially extending second groove. One of the grooves is superimposed relative to the other groove to define therewith a space. A wire extends within the space to hold the button disk on the cutter.

The present application claims priority under 35 U.S.C. §119 to PatentApplication Serial No. 0402051-7 filed in Sweden on Aug. 20, 2004.

FIELD OF THE INVENTION

The present invention relates to a tool, a cutter and a button disk formining of rock material by means of undercutting.

In WO-A1-03001031 a device is shown that breaks rock material with theassistance of a tool that uses undercutting to rationally breakquantities of rock material without creating much dust. However, theknown tool has shown to be expensive to use.

OBJECTS OF THE INVENTION

One object of the present invention is to provide a cutter and a buttondisk which give the same advantages as the prior art.

Another object of the present invention is to provide a cutter with goodstability.

Still another object of the present invention is to provide a cutterwith a good life-span.

Still another object of the present invention is to provide a cutter,which is inexpensive to use.

Still another object of the present invention is to provide aninterchangeable button disk.

These and other objects have been achieved by means of a tool for miningrock preferably by means of undercutting. The tool comprises anattachment part which defines a center longitudinal axis, and a holdermounted to the attachment part by bearings for rotation relative theretoabout the axis. An outer surface of the holder includes acircumferentially extending first groove. A button disk is mounted onthe cutter and includes an inner surface having a circumferentiallyextending second groove. One of the grooves is superimposed relative tothe other groove to define therewith a space. A wire extends within thespace to hold the button disk on the cutter.

Another aspect of the invention relates to the cutter which defines anaxis of rotation and comprises a holder, a button disk mounted to afront portion of the holder, and a wire oriented in a space defined bymutually superimposed circumferential grooves of the holder and thebutton disk, for securing the button disk to the holder.

Yet another aspect of the invention relates to a button disk adapted tobe rotatably journaled on a holder and defining an axis of rotation. Thebutton disk carries rock breaking elements at a front portion thereofand includes a circumferential groove adapted to receive a wire forattaching the button disk to the holder.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and advantages of the invention will become apparent fromthe following detailed description of a preferred embodiment thereof inconnection with the accompanying drawing in which like numeralsdesignate like elements, and in which

FIG. 1 shows a cutter according to the present invention in a partlycross-sectional side view.

FIG. 2 shows an exploded view of a tool in a partly cross-sectional sideview, including a cutter and a button disk according to the presentinvention.

FIG. 3 shows a button disk according to the present invention incross-section according to line III-III in FIG. 2.

DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 2 shows a tool 10 for mining of rock material preferably by meansof undercutting. The tool comprises an elongated attachment part 11 acutter 12. The attachment part 11 has a substantially parallelepipedicalcross-section and comprises essentially plane parallel lower and uppersides united by substantially plane parallel connector surfaces, i.e. asupport surface and a free surface, and an end surface. The undersideand the support surface form an internal second acute angle, which isfrom 70° to 85°.

A bearing journal 13 is formed integrated with the attachment part 11,whereby the cutter 12 is mounted on the journal 13 for rotation about acenter axis CL. The cutter 12 comprises substantially three separateparts, i.e. a holder 40, a button disk 112 and a wire 24.

The cutter 12 has a number of rock breaking means, preferably in theform of hard metal buttons 14, arranged in an annular row at a distancefrom each other in the circumferential direction of the cutter 12. Saiddistance is at least double the diameter of the button 14. By theexpression “hard metal” is here meant a metal carbide, such as tungstencarbide (TC) or similar, sintered together with a binder phase, such ascobalt (CO) or nickel (Ni). A number of bearing arrangements areprovided between the cutter 12 and the journal 13. The cutter 12 issymmetrical and rotatable relative to the journal 13 about therotational axis CL such as is more closely described in WO-A1-03001031.

The button disk 112 is preferably substantially symmetrically configuredabout a rotational axis CL and is stationary relative to a protrusion113 of the journal 13. The cutter 12 has an external cylindrical surface15 to receive radially directed forces. The cylindrical surface 15 isprovided in connection with a first end of the cutter 12 which facesaway from the attachment part 11. A shoulder or abutment surface 29oriented perpendicular to the rotational axis CL is provided on theprotrusion to receive axial forces. The shoulder 29 connectsperpendicularly to the surface 15. The shoulder 29 is provided on acylindrical base 36 connected to the attachment part 11. The base 36transfers into the attachment part 11 via a stop surface 50. The stopsurface 50 has a greater radial extension than the attachment part 11and is perpendicular to the rotational axis CL. A circumferential groove23A is provided in the surface 15. The groove 23A has a substantiallysemi-circular cross-section. The groove 23A is provided at a distancefrom the shoulder 29, which distance is shorter than 50% of the axialextension of the surface 15, preferably shorter than 40% of the axialextension of the surface 15.

The button disk 112 has substantially the shape of a circle. The buttondisk 112 comprises a substantially planar, open first end surface 31,which is perpendicular to the rotational axis CL and which connects to asubstantially conical peripheral surface. The peripheral surfacecomprises holes which hold the buttons 14. The peripheral surfacefurther connects to an axially rearward tapering outer surface 33, whichby wiry minerals has a breaching function. The surface 33 may includewear protection in the shape of a hard weld or a number of hard metalbuttons 14. The surface 33 further connects to a cylindrical jacketsurface 32 of the button disk 112. Said jacket surface 32 can bearranged radially outside of an imaginary cylinder that the jacketsurface of the cylindrical base 36 forms.

The button disk 112 comprises a substantially planar open second endsurface or abutment surface 34, which is perpendicular to the rotationalaxis CL and connects to the cylindrical jacket surface 32.

The button disk comprises a central cylindrical hole 35 whose wallconstitutes an internal cylindrical surface 16. A circumferential groove23B is provided in the surface 16. The groove 23B has a substantiallysemi-circular cross-section. The groove 23B is provided at a distancefrom the second end surface 34, which distance is shorter than 50% ofthe axial extension of the surface 16, preferably shorter than 40% ofthe axial extension of the surface.

Buttons 14 of hard metal are fixed along a circumferential protrusion 30on the button disk 112. The center line CL2 of each button forms anacute angle with the rotational axis CL of the cutter. The angle is from60 to 80°, preferably about 75° An extension of the center line CL2 ofeach button intersects the rotational axis CL at a point X axiallyrearwardly of the groove 23B or the wire 24, see below. The term“rearwardly” here means that the extension line intersects therotational axis CL on the attachment part 11 side of the groove 23B orthe wire 24.

A hole 25 running tangentially from the groove 23B in the surface 16(see FIG. 3) exits in the conical surface 33. The hole 25 is provided toenable insertion of a wire 24 of high-tensile steel; such as for examplespring steel, into a space defined by superimposed grooves 23A, 23B. Thewire 24 in the shown embodiment has a circular cross-section but canalso have other cross-sections, such as a rectangular cross-sectionwhereupon the grooves 23A, 23B would form a corresponding space. Thewire has a cross-sectional area that is smaller than the cross-sectionalarea of the space formed by the grooves 23A, 23B to simplify insertion.

The tool 10 is mounted as follows. The attachment part 11 and the buttondisk 112 are aligned with the rotational axis CL, whereafter the buttondisk is pushed over the protrusion 113 such that the surfaces 15 and 16slide against each other until the surfaces 34 and 29 abut against eachother. Thereby, also the grooves 23A and 23B are aligned (mutuallysuperimposed) such that an essentially circular cross-sectional space iscreated, as illustrated by FIG. 1. Thereby the wire 24 can be insertedthrough the hole 25 and into the formed space. Since the wire iselastically moldable the wire will follow the space until this itsubstantially fills the space. The wire 24 preferably has a length thatat least corresponds to the length of the groove 23A. Preferably, theinsertion of the wire is finalized with the aid of a narrow assister,which then is retracted when the wire has attained the desired position.The wire 24 will substantially prevent relative rotation of theprotrusion 113 and the button disk 112 and is intended to secure theposition of the button disk on the attachment such that the disc doesnot fall off of the attachment.

The hole 25 need not be sealed after the insertion of the wire 24. Thesurfaces 29 and 34 receive all reactional force from the rock being cut,while the principal task of the wire 24 is to retain the button disk 112on the protrusion 113. The power that is required to shear the wire 24must be so great that it in principle becomes impossible for this tohappen, neither during work nor at disk change. Instead the button diskcan be cut up into sections in for example two places. The hole 25 isused only for insertion of the wire. The surfaces 15 and 16 havesubstantially the same axial extension.

The tool 10 is intended to be mounted to a device in a machine, notshown, such that the stop surface 50 of the tool 10 may abut against astop surface of the device. The attachment part 11 and the machine to beused with the tool 10 have been described in WO-A1-03001 031, whichhereby is incorporated into the present description regarding theattachment part 11 and the machine. For example, by tilting the tool, agreater clearance is obtained for inactive parts of the tool, and a morefavorable angle of attack for active buttons 14 is obtained. The tool isforemost intended for ore mining such as platinum ore, where the orelies in narrow reefs in the rock. Frequently, three of the buttons 14 ofthe tool are active simultaneously, which gives a great surface pressureper hard metal button in relation to surface pressure at steel disksaccording to other prior art. This gives good penetration per button andrequires smaller energy at the same time as the drill cuttings are notcompressed in the formed groove but find accommodation between thebuttons, which entails good life-span for the tool.

The present invention consequently relates to a tool, a cutter and abutton disk that use undercutting to rationally break a great amount ofrock material without creating much dust. The tool is simple, has goodstability and a good lifespan. The tool is inexpensive to use since thebutton disk is interchangeable.

Although the present invention has been described in connection with apreferred embodiment thereof, it will be appreciated by those skilled inthe art that additions, deletions, modifications, and substitutions notspecifically described may be made without departing from the spirit andscope of the invention as defined in the appended claims.

1. A tool for mining rock, comprising: an attachment part defining acenter longitudinal axis, a holder mounted to a front portion of theattachment part by bearings for rotation relative thereto about theaxis, an outer surface of the holder including a circumferentiallyextending first groove, a button disc mounted on the holder andincluding an inner surface having a circumferentially extending secondgroove, wherein one of the grooves is superimposed relative to the othergroove to define therewith a space; and a wire extending within thespace to hold the button disc on the cutter.
 2. The tool according toclaim 1 wherein the button disc includes hard metal buttons arranged inan annular row along an outer periphery of the button disc, a centerline of each button disc intersecting the axis at a point locatedaxially rearwardly of the wire.
 3. The tool according to claim 1 whereinthe button disc includes an internal surface overlying an externalsurface of the holder, the button disc including a rearwardly facingabutment surface abutting a forwardly facing abutment surface of theholder, each groove spaced by an axial distance from the abutmentsurfaces, the distance being shorter than 50% of an axial extension ofthe internal surface.
 4. The tool according to claim 3 wherein thedistance is shorter than 40% of the axial extension.
 5. The toolaccording to claim 1, wherein the wire has a length substantiallycorresponding to a length of the space.
 6. A cutter for mining rockmaterial, the cutter defining an axis of rotation and comprising aholder, a button disk mounted to a front portion of the holder, and awire oriented in a space defined by mutually superimposedcircumferential grooves of the holder and the button disc, for securingthe button disk to the holder.
 7. The cutter according to claim 6,further including hard metal buttons arranged in a generally annular rowalong an outer periphery of the button disc; each button defining acenter line which intersects the axis at a point located axiallyrearwardly of the wire, the button disc including an internal surface inwhich one of the grooves is formed.
 8. The cutter according to claim 7wherein the button disc includes a rearwardly facing abutment surfacefor abutting the holder, the groove of the button disc spaced forwardlyfrom the abutment surface by a distance shorter than 50% of the axiallength of the internal surface.
 9. The cutter according to claim 8wherein the distance is shorter than 40% of the axial length.
 10. Thecutter according to claim 6 wherein the button disc includes a centralcylindrical hole defined by the internal surface.
 11. A button discadapted to be rotatably journaled on a holder and defining an axis ofrotation; the button disc carrying rock breaking elements at a frontportion thereof and including a circumferential groove adapted toreceive a wire for attaching the button disc to the holder.
 12. Thebutton disc according to claim 11 wherein the button disc includes aninternal surface in which the groove is formed.
 13. The button discaccording to claim 12 wherein the internal surface defines a centralcylindrical hole passing through the button disc.
 14. The button discaccording to claim 13 further including a rearwardly facing abutmentsurface; the groove spaced forwardly from the abutment surface by adistance shorter than 50% of an axial length of the hole.
 15. The buttondisc according to claim 14 wherein the distance is shorter than 40% ofthe axial length.